1. Field of the Invention
Aspects of the present invention relate to a battery, and more particularly, to a battery pack that can increase a length of a bare cell, relative to the length of the battery pack, and can be produced by a simplified manufacturing process.
2. Description of the Related Art
Lithium secondary battery have an operating voltage of 3.6V, which is three times the operating voltage of a nickel-cadmium battery or a nickel-hydrogen battery, which are commonly used power sources for portable electronic devices. In addition, lithium secondary batteries have higher energy densities per unit weight. Accordingly, lithium secondary batteries have been widely used in portable wireless devices, and in other technological fields.
Generally, a lithium secondary battery is manufactured as a battery pack. The battery pack usually includes a bare cell, a protective circuit board, and a molding part or case that covers the protective circuit board.
The bare cell includes a rechargeable electrode assembly, a can having an upper opening to receive the electrode assembly, and a cap assembly to seal the upper opening of the can. The bare cell includes a negative terminal that is electrically coupled to a negative electrode of the electrode assembly, and to a cap plate of the cap assembly.
The protective circuit board is electrically coupled to the negative terminal of the bare cell, and to the cap plate. The protective circuit board is connected to the cap plate, by a lead plate vertically combined to the cap plate. In addition, the protective circuit board is connected to the negative terminal, by another lead plate vertically extended from the negative terminal. A separate connection lead is extended downward from the protective circuit board, and welded to the lead plate.
The molding part or case is formed to surround the protective circuit board, at the upper part of the bare cell, thereby protecting the protective circuit board. However, the length of the battery pack is increased, because the bare cell and protective circuit board are connected by the separate conductive member, such as the vertically extended lead plate and the connection lead. In other words, the connection lead of the protective circuit board and the lead plate increase the length of the battery pack, and thereby reduce the capacity per total volume of the battery.
The connection lead and lead plate are combined in the following process. First, the protective circuit board and bare cell are fixed by a separate jig, so that the connection lead and lead plate contact each other. The protective circuit board is arranged perpendicular to the upper surface of the bare cell. Then the connection lead and lead plate are welded. The protective circuit board is arranged in parallel with the upper surface of the bare cell, by bending the lead plate. Thus, the bare cell and protective circuit board are combined through a complicated process.